This disclosure relates to an optical apparatus capable of exposing a large-area substrate.
In recent years, display apparatuses have been getting bigger in size in accordance with customer demand. Accordingly, a variety of processing equipment for manufacturing large display panels is being researched and developed. Among this equipment, an exposure apparatus is a major apparatus for deciding sizes of micro-patterns in large display panels. The exposure apparatus may transfer the micro-patterns onto a substrate of a display panel. Displacement or vibration of the exposure apparatus may frequently result in defects on the micro-patterns. Thus, the exposure apparatus may include position detectors for monitoring displacement of an optical system. The position detectors may include an electronic sensor or a differential interferometer. The electronic sensor may reduce thermal safety of the exposure optical system. The differential interferometer may measure displacement of the exposure optical system in comparison with a reference object for measuring. The differential interferometer may be generally used for a single measurement object. However, the differential interferometer may be inappropriate for measuring the variability of a plurality of exposure optical systems.